Question:

(a) One problem encountered when designing web applications is that HTTP is a "stateless" protocol. Explain two general approaches to solve the statelessness problem.

(b) Describe how a User Control is declared in an ASP.NET page. Illustrate your answer using extract codes.

(c) Distinguish between the following ASP.NET properties:

(i) IsPostBack
(ii) AutoPostBack.

(d) Prepare an ASP.NET program with the specifications given below:

(i) Create a DropDownList control declaratively with three items: Select Colour, Red and Blue

(ii) A user must not be able to submit the form if he chooses the Select Colour item

(iii) The form is only submitted if a user selects either Red or Blue

(iv) Detect the chosen colour and prints a message as follows: "Red colour chosen" or "Blue colour chosen".